068 - Stop Blaming the Theme: What's Really Killing Your Shopify Store's Speed
Liquid Weekly Podcast: Shopify Developers Talking Shopify DevelopmentShow Notes
Shopify performance specialist Izaac Barratt of Baseline Commerce joins Karl and Taylor for a deep dive into site speed optimization. The conversation covers the full spectrum from LCP and INP fundamentals to the real-world friction of app bloat, AI coding habits, and what actually moves the needle for conversion rates. A must-listen for any theme developer, app developer, or agency working with high-traffic Shopify stores.
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Find Izaac Barratt Online LinkedIn: https://www.linkedin.com/in/izaac-barratt — where he posts performance tips, resources, and his ongoing series on the nine performance fix buckets Baseline Commerce: baseline-commerce.com — Izaac's site speed optimization consultancy
Timestamps 01:23 – Intros; welcoming guest Izaac Barrett 02:48 – Izaac's origin story: animation, Newgrounds, and e-commerce 05:36 – What drew Izaac to performance optimization 06:00 – First site speed project: 12 seconds to 2 seconds, conversion doubled 10:00 – LCP fundamentals: above-the-fold prioritization and perception 18:00 – Preloading, lazy loading, and how to get them wrong 20:43 – Liquid's preload tag, sections_index, and reducing JavaScript dependency 26:38 – Telling AI to prioritize HTML/Liquid and CSS over JavaScript 31:01 – Async vs. defer vs. render-blocking scripts explained 35:28 – Apps and performance: identifying problem apps, merchant conversations 39:15 – Advice for app developers on loading strategy and user interaction cycles 41:42 – INP (Interaction to Next Paint) explained: what it is and why it's hard to fix 43:30 – Shopify/research report: 34ms of INP = 3.5% drop in CVR 46:06 – How to debug INP: Chrome DevTools performance tab and CrUX data 53:20 – Izaac's LinkedIn series: nine buckets of performance fixes 56:17 – Dev Changelog 1:02:44 – Picks of the Week
Dev Changelog - Next-Generation Events — Developer Preview: https://shopify.dev/changelog - ⚠️ Expiring Offline Access Tokens Required for All Public Apps — January 1, 2027: https://shopify.dev/changelog - Shop Minis — March/April 2026 Update: https://shopify.dev/changelog - Customer Account UI — Feature Preview: https://shopify.dev/changelog - App Home as a UI Extension: https://shopify.dev/changelog- llms.txt / agents.md in Shopify Themes: https://shopify.dev/changelog
Picks of the Week Karl: The Dark Journey: The Tragedy of the Donner Party by Allan Eckert – A true history of the ill-fated 1846 wagon party, written by one of Karl's favorite frontier authors; dark but compelling, especially for history enthusiasts. https://www.amazon.com/Dark-Journey-Allan-W-Eckert/dp/1931672539
Izaac: Page Speed Impact Estimator fastersite.ai – A tool for estimating the performance gains of removing specific scripts and assets before actually doing the work; great for benchmarking and scoping conversations with clients.
Taylor: The Will of the Many by James Islington – A sci-fi novel recommended by Taylor's brother (a bookseller); follows a teenager hiding his royal lineage in a Roman Empire-style society that literally harvests people's will to gain power. Book two also out. https://www.goodreads.com/book/show/58416951-the-will-of-the-many
More from Liquid Weekly Podcast: Shopify Developers Talking Shopify Development
Taylor is in India for Shop Quest, so Karl flies solo with Charles Swayne, owner and app developer at JadePuma Apps and the person behind Datify. Charles is 21, learned Python in sixth grade, and now runs a multi-agent development workflow that researches, plans, audits the plan, executes, and tests itself before he ever looks at the code.
Georgi Petrov, CEO and co-founder of Uxify, joins Karl and Taylor to talk about the half of web performance nobody optimizes for: the shopper's device. After building SMS Bump (acquired by Yotpo), ConsentMo, and NitroPack (acquired by WP Engine), Georgi is now tackling device-specific friction, the laggy buttons, layout shifts, and interaction delays that vary wildly from one phone to the next. We get into how Uxify profiles a visitor's capability without touching your code, the specialized agents that fix problems on the fly, the ClickHouse-powered data layer behind it all, and how to think about performance heading into BFCM. Plus the Dev Changelog and Picks of the Week. Sponsor The Support Heroes: https://www.thesupportheroes.com/ Subscribe to Liquid Weekly Don't miss out on expert insights and tips. Subscribe to Liquid Weekly for more content like this: https://liquidweekly.com/ Find Georgi Online Uxify: https://uxify.com/integrations/shopify/ LinkedIn: https://www.linkedin.com/in/georgipetrov/ Timestamps (00:00) Open (00:29) Intros (02:11) Meet Georgi Petrov of Uxify (02:54) Origin story: hardware hacking to his first software (06:03) Finding Shopify: SMS Bump, ConsentMo, and NitroPack (12:23) Making fast decisions and failing cheaply (15:32) Why Uxify: performance is half website, half device (20:11) How it works: profiling devices and adapting on the fly (26:17) Sitting alongside your theme without touching your code (28:26) Real user monitoring and specialized agents (37:47) The tech stack: ClickHouse and heavy browser testing (41:57) Shopify cart variations and a clever checkout fallback (46:24) Prepping for BFCM and who Uxify is for (51:14) Dev Changelog (58:22) Picks of the Week Dev Changelog [action required] Variants now support multiple barcodes: https://shopify.dev/changelog/product-variant-barcode-is-being-replaced-by-barcodes Create and delete dev stores in Shopify CLI: https://shopify.dev/changelog/create-and-delete-dev-stores-in-shopify-cli [action required] Discounts Allocator Function API developer preview has ended: https://shopify.dev/changelog/discounts-allocator-function-api-developer-preview-has-ended Delivery options in Shopify Functions input now expose their metafields: https://shopify.dev/changelog/delivery-options-in-shopify-functions-input-now-expose-their-metafields Prepare your app for the Shopify admin's new look: https://shopify.dev/changelog/prepare-your-app-for-the-shopify-admins-new-look [action required] Updates to Events payloads and subscription configuration: https://shopify.dev/changelog/updates-to-events-payloads-and-subscription-configuration New Pricing audit trail for contextual product variant prices: https://shopify.dev/changelog/pricing-audit-trail-for-contextual-product-variant-prices [breaking api change] [action required] Removed session.currentSession.staffMemberId from POS UI Extensions (2026-10): https://shopify.dev/changelog/removed-session-currentsession-staffmemberid-from-pos-ui-extensions-2026-10 Request a bundle size exception for existing UI extensions: https://shopify.dev/changelog/request-a-bundle-size-exception-for-existing-ui-extensions Picks of the Week Karl: Keto Oreo-style sandwich cookies (about 50 calories each), part of his ongoing tour through packaged keto snacks: https://www.choczero.com/products/keto-sandwich-cookies Georgi: Calisthenics between AI prompts. Knocking out push-ups and squats while waiting on an agent, which he says burns the time well and sharpens his focus when he comes back. Taylor: Ted Lasso, season 4 on Apple TV+. Still, in his words, one of the most wholesome shows around: https://www.imdb.com/title/tt10986410/
Prakhar Shrivastava of FoxSell joins Karl and Taylor to talk about Shop Quest, the Shopify community event he and his team run in Bengaluru, and to prep Taylor for his first trip to India.
In this episode of the Liquid Weekly Podcast, hosts Karl Meisterheim and Taylor Page are joined by Alexander Hupfer, founder of Fusion Metrics and a solo Shopify app developer.
Episode 073 – I Hid Swag and I'd Do It Again! - Recapping our DotDev Adventure